Ramda

A practical functional library for Javascript programmers.

Why Ramda?

There are already several excellent libraries with a functional flavor. Typically, they are meant to be general-purpose toolkits, suitable for working in multiple paradigms. Ramda has a more focused goal. We wanted a library designed specifically for a functional programming style, one that makes it easy to create functional pipelines, one that never mutates user data.

What's Different?

The primary distinguishing features of Ramda are:

Ramda emphasizes a purer functional style. Immutability and side-effect free functions
are at the heart of its design philosophy. This can help you get the job done with simple,
elegant code.

Ramda functions are automatically curried. This allows you to easily build up new functions
from old ones simply by not supplying the final parameters.

The parameters to Ramda functions are arranged to make it convenient for currying. The data
to be operated on is generally supplied last.

The last two points together make it very easy to build functions as sequences of simpler functions, each of which transforms the data and passes it along to the next. Ramda is designed to support this style of coding.

Philosophy

Using Ramda should feel much like just using Javascript.
It is practical, functional Javascript. We're not introducing
lambda expressions in strings, we're not borrowing consed
lists, we're not porting over all of the Clojure functions.

Our basic data structures are plain Javascript objects, and our
usual collections are Javascript arrays. We also keep other
native features of Javascript, such as functions as objects
with properties.

Functional programming is in good part about immutable objects and
side-effect free functions. While Ramda does not enforce this, it
enables such style to be as frictionless as possible.

We aim for an implementation both clean and elegant, but the API is king.
We sacrifice a great deal of implementation elegance for even a slightly
cleaner API.

Last but not least, Ramda strives for performance. A reliable and quick
implementation wins over any notions of functional purity.

(note that using latest is taking a significant risk that ramda API changes could break your code.)

These script tags add the variable R on the browser's global scope.

Or you can inject ramda into virtually any unsuspecting website using the bookmarklet.

Build

on Unix-based platforms, npm run build updates dist/ramda.js and dist/ramda.min.js

on Windows, write the output of scripts/build --complete to a temporary file, then rename the temporary file dist/ramda.js.

Partial Builds

It is possible to build Ramda with a subset of the functionality to reduce its file size. Ramda's build system supports this with command line flags. For example if you're using R.compose, R.reduce, and R.filter you can create a partial build with:

Documentation

Introductions

The Name

Ok, so we like sheep. That's all. It's a short name, not already
taken. It could as easily have been eweda, but then we would be
forced to say eweda lamb!, and no one wants that. For non-English
speakers, lambs are baby sheep, ewes are female sheep, and rams are male
sheep. So perhaps ramda is a grown-up lambda... but probably not.

Running The Test Suite

Console:

To run the test suite from the console, you need to have mocha installed:

npm install -g mocha

Then from the root of the project, you can just call

mocha

Alternately, if you've installed the dependencies, via:

npm install

then you can run the tests (and get detailed output) by running:

npm test

Browser:

To run the test suite in the browser, you can simply open test/index.html.

Alternatively, you can use testem to
test across different browsers (or even headlessly), with livereloading of
tests too. Install testem (npm install -g testem) and run testem. Open the
link provided in your browser and you will see the results in your terminal.

If you have PhantomJS installed, you can run testem -l phantomjs to run the
tests completely headlessly.